In the United States, the 1.92-1.93GHz frequency range has been allocated to Unlicensed Personal Communications Services (UPCS). There are however incumbent microwave users of the 1.92GHz band who must be protected from potential interference by UPCS radio transmissions. A committee known as UTAM Inc. (Unlicensed Transition And Management for Microwave Relocation in the 2GHz Band), was formed and given the mandate to ensure that the deployment of UPCS does not interfere with these incumbent users. It also ensures that a new installation cannot be activated, until its location has been coordinated by UTAM Inc., as defined by the rules set forth below.
A UPCS or PCS system is a pico-cellular system which utilizes Cordless Fixed Parts (CFP)s--base stations, and Cordless Portable Parts (CPP)s--portable handsets, that operate with very low radiated power, to communicate with each other.
The Federal Communications Commission (FCC), in the United States of America, has generated a set of rules which require manufacturers to provide `automatic` mechanisms to detect geographic movement of these systems. It is the responsibility of UTAM Inc. to follow the rules set out by the FCC. Upon detection of such movement, a system must not operate until the new area is verified by a UTAM, Inc. representative.
This is manifest by the following clauses taken directly from the FCC Spectrum Etiquette Part 15--Subpart D--Unlicensed PCS Devices which is a regulatory document to which systems and devices must comply. The following are the rules which require automatic provisions to detect movement and disable the systems:
15.307c An application for certification of PCS device that is deemed by UTAM, Inc. to be noncoordinatable will not be accepted until the Commission announces that a need for coordination no longer exists. PA1 15.307d A coordinatable PCS device is required to incorporate means that ensure that it cannot be activated until its location has been coordinated by UTAM, Inc. The application for certification shall contain an explanation of all measures taken to prevent unauthorized operation. This explanation shall include all procedural safeguards, such as the mandatory use of licensed technicians to install the equipment, and a complete description of all technical features controlling activation of the device. PA1 15.307e A coordinatable PCS device shall incorporate an automatic mechanism for disabling operation in the event it is moved outside the geographic area where its operation has been coordinated by UTAM, Inc. The application for certification shall contain a full description of the safeguards against unauthorized relocation and must satisfy the Commission that the safeguards cannot be easily defeated. PA1 15.307h The operator of a PCS device that is relocated from the coordinated area specified by UTAM, Inc., must cease operating the device until coordination for the new location is verified by UTAM, Inc.
These rules: 1) are intended to allow for the coexistence of differing protocols and air-interfaces, from various equipment manufacturers within the UPCS spectrum band; and 2) with respect to UTAM Inc. are intended to protect the microwave incumbents. Various disablement tests may be utilized to detect movement of the PCS system outside its geographic area of operation. The following is a review of some of these tests:
1. Global Positioning System: Hand held GPS systems are available for the consumer electronic market. Software could be developed to manage the location coordinates and subsequently verify that they have not changed, each time the system is restarted. However, it would be costly to integrate a GPS unit into a hardware packaging and software architecture of a PCS system. Furthermore, GPS units may not function adequately indoors; PA0 2. Time Of Day Clock: The "suggested" UTAM Disablement Test Suite, requires the system to be stored for 8 hours, to simulate the movement from the original location, to the new location. Software could be developed to detect an 8 hour (or greater), power outage. However, when the system does not support a "Time Of Day" clock, and the system is powered down, the system clock stops, and will be restarted at the time of day it stopped at, when the system is powered up at the new location. Hence, the system does not have a concept of elapsed time, when powered down. Furthermore, it is quite possible for the system to be relocated within the 8 hour period. Again, this solution would entail costly hardware enhancements; PA0 3. Mercury Switch: A motion sensitive mercury switch could be attached to a system controller during installation, which would be designed to "break" its contacts, in the event of movement. The contacts could be strategically connected to prevent the system from operating, if they are opened. However, motion sensitivity would be an issue, and again, hardware packaging and security would also be an issue; PA0 4. Correlating Hardware IDs: Every base station is manufactured with a unique "Hardware Identification code". The system maintains information on the "Hardware ID", associated with the physical "Port ID" on the controller, in which the base station has been connected. It is possible to detect "Port ID" and "Hardware ID" mismatches, as a means of inferring that "geographic" movement has occurred, if the customer failed to reconnect the base stations to their original ports, after "moving" the system. However, it is likely that the customer would carefully label the original ports, where the base stations were connected and would replace them as they were, after a "move". Hence, this scheme would be easily defeated. In addition, this scheme would be a nuisance when replacing defective base stations, since a new replacement base station will have a different "Hardware ID" and could cause the system to incorrectly determine that "geographic" movement has occurred.